严重烫伤小鼠主要器官自噬变化的实验研究

Changes of autophagy in the internal organs of severely scalded mice

目的严重烧伤后常发生主要器官结构与功能损害,其发生机制尚不完全明确。文中旨在通过初步观察严重烫伤早期不同时相点小鼠主要器官的自噬变化情况,为研究自噬在严重烧伤后器官结构与功能损害中的作用奠定基础。方法选取BALB/C小鼠24只,随机分为6组,即烫伤前组(正常对照)、烫伤后1h、2h、6h、12h和24h组,烫伤各组常规制备30%总体表面积(total body surface area,TBSA)Ⅲ度烫伤小鼠模型。采集各组动物的心、肝、肺、肾组织,用免疫印迹法检测自噬相关蛋白Beclin 1、LC3蛋白表达,透射电镜观察细胞内自噬溶酶体情况。结果小鼠烫伤后1h心、肝、肺、肾组织Beclin 1较烫伤前逐渐增加[(0.70±0.19)vs(0.60±0.16)、(0.95±0.11)vs(0.65±0.20)、(0.88±0.08)vs(0.80±0.07)、(0.82±0.12)vs(0.70±0.14)],烫伤后1 h LC3蛋白表达较烫伤前逐渐增加[(3.48±1.25)vs(2.58±0.93)、(1.24±0.52)vs(0.91±0.24)、(1.12±0.27)vs(0.87±0.29)、(1.05±0.41)vs(0.68±0.21)],肝、肺、肾组织Beclin 1(1.37±0.18、1.27±0.06、1.51±0.20)及LC3蛋白表达(2.03±0.57、1.66±0.59、2.12±0.75)于伤后12 h达高峰,随后回落,但至伤后24h时仍高于正常对照。心组织Beclin 1及LC3蛋白表达则是持续性逐渐增加,至伤后24h时仍显著高于正常对照。透射电镜下烫伤小鼠心、肝、肺、肾组织细胞内自噬溶酶体较正常对照增多。结论严重烫伤后器官细胞自噬增加,可能在烫伤后器官组织结构与功能变化中起着重要作用。

Objective Structural and functional damages of internal organs often occur in severe burns, and the underlying mecha- nisms are not yet completely understood. The aim of this study is to investigate the change of autophagy in internal organs in severely scalded mice, including the heart, liver, lungs and kidneys, so as to get an insight into the role of autophagy in the damage of internal organs in se-vere burns. Methods Twenty-four BALB/C mice were randomiy divided into a prescald control group and five （1, 2, 6, 12 and 24 h） postscald groups, the latter five groups subjected to full-thickness scald of 30% total body surface area. Tissue samples from the heart, liver, lungs and kidneys were harvested for detection of the expressions of the Beclin-1 and LC3 proteins by Western blot and observation of autoph- agic lysosomes under the transmission electron microscope. Results The expressions of Beclin-1 and LC3 began to increase in the heart, liver, lungs and kidneys of the scalded mice at 1 hour after scald as compared with the controls, peaked in the liver, lungs and kidneys at 12 hours, and then decreased, but still higher than in the control group at 24 hours. The expressions of the two proteins were increased steadily in the heart of the scalded mice, significantly higher than those of the controls even at 24 hours. Transmission electron microscopy revealed increased numbers of autophagic lysosomes in the heart, liver, lungs and kidneys after scald. Conclusion Enhanced autophagy in internal organs may play an important role in the damage of the structure and function of the organs in severe scald.